This project is to determine the in vivo loading data from total knee joint replacements. These new joint replacements will have incorporated within the body of the femoral components all the required telemetry circuitry to telemeter from the device three channels of loading data. One channel will be used to record the axial load on the device, the other two to record the tangential forces about two orthogonal axes normal to the long axis of the femur. The medial and lateral tracks of the femoral component will be independent in order to avoid coupling interactions.